This invention relates to a structure of a gas discharge display panel and a gas discharge display device.
Gas discharge display devices, such as a plasma display device and the like, produce a display through self-luminescence and, therefore, are characterized in that the field angle is large, the display is easy to see, the thickness can be reduced, and a large picture plane can be realized. Thus, such gas discharge display devices have been used extremely as display devices of information terminal equipment and high-quality picture tubes for television.
Plasma displays are roughly classified into a direct current driving type and an alternate current driving type. Among them, the alternate current type of plasma display exhibits a high luminance owing to the memory action of a dielectric layer covering the electrodes, and its lifetime has reached a practical level through formation of a protective layer thereon. This results in practical application of plasma displays to video monitors for many uses.
FIG. 10 is a perspective view illustrating the structure of a conventional plasma display panel, wherein the front side substrate 100 is separated from the back side substrate 200 to expose a discharge space region 300 for the purpose of facilitating understanding of the structure. The front side substrate 100 comprises display electrodes 600 made of a transparent conductive material such as ITO (indium tin oxide), tin oxide (SnO2) or the like, a bus electrodes 700 made of a low-resistance material, a dielectric layer 800 made of a transparent insulating material and a protecting layer 900 made of magnesium oxide (MgO) or the like, all being formed on a front side glass substrate 400.
The back side substrate 200 comprises address electrodes 1000, barrier ribs 1100 and a fluorescent material layer 1200, all formed on a back side glass substrate 500. Although not shown in FIG. 10, a dielectric layer 1300 is formed on the address electrodes 1000 as well. By affixing the front side substrate 100 to the back side substrate 200 so that the display electrodes 600 form an approximately right angle with the address electrodes 1000, a discharge space region 300 is formed between the front side substrate 100 and the back glass side substrate 500.
In this gas discharge display panel, an alternating current voltage is applied between one pair of display electrodes 600 provided on the front side substrate 100, and a voltage is applied between an address electrode 1000 provided on the back side substrate 200 and a display electrode 600, whereby an address discharge is made to occur and a main discharge is generated in a prescribed discharging cell. The main discharge generates ultraviolet rays, which produces emission of light from the red-, green- and blue-color fluorescent materials 1200 separately coated on respective discharging cells. A display is produced by emission of such light.
An example of such prior gas discharge display devices of this type are described in, for instance, FLAT PANEL DISPLAY 1996 (edited by Nikkei Microdevice, 1995), pages 208-215.
Now, a major desire in the gas discharge display device field is to shorten the manufacturing time of the gas discharge display device. For shortening the manufacturing time of the gas discharge display device, we have developed a method to form display electrodes 600 and bus electrodes 700 on a front substrate 100 using a laser process instead of using the more common photolithography process. The laser process does not require masks and resist, which are used in the photolithography process, to form wiring on a substrate. So the laser process is an advantageous technique from the point of view of product cost, as well as production time.
However, the laser equipment used for such manufacture doesn""t scan in an oblique direction, but must scan a beam or a stage in the XY direction to form obliquely directed wiring on the substrate. On the other hand, the display electrodes 600 and bus electrodes 700 of the gas discharge display device have obliquely directed wiring. The obliquely directed wiring is connected to an external connection terminal, and lies outside of a display area of the gas discharge display panel. The display area is an area which operates as a substantial picture display region.
Accordingly, when this oblique wiring is processed by the laser equipment, this laser forming of the oblique wiring needs more than double the manufacturing time of a laser forming of a straight line wiring because the laser equipment is able to scan a beam or a stage in only the XY direction to form obliquely directed wiring on the substrate.
It is an object of the present invention to provide an improved, gas discharge display panel and gas discharge display device using laser processing so that the time required to form wiring on a substrate thereof is shortened.
In order to achieve the object mentioned above, this invention provides a gas discharge display panel which is provided with a first substrate having a plurality of first electrodes and a plurality of second electrodes, said first electrodes being formed with approximately a rectangular form by a laser process, said second electrodes being formed on the first electrodes, and a second substrate having a plurality of third electrodes and being opposed to the first substrate.
Further, it is desirable that said second electrodes are formed either by a photolithography process or a laser process, and said first electrodes are formed by a laser process after the second electrodes are formed by the photolithography process or the laser process.
Further, it is desirable that said first electrodes are made of the transparent material, such as ITO (Indium Tin Oxide) or SnO2, and said second electrodes are made of a material, such as Ag or Cr/Cu/Cr layers, the resistance value of such material being lower than that of the transparent material.
Further, this invention forms a gas discharge display device provided with a gas discharge display panel including a first substrate having a plurality of first electrodes and a plurality of second electrodes, said first electrodes being formed with approximately a rectangular form by a laser process, and said second electrodes being formed on the first electrodes and being formed to extend from the first electrode to an external connection terminal, and a second substrate having a plurality of third electrodes and being opposed to the first substrate, and a drive circuit electrically connected to the external connection terminal of the gas discharge display panel.
Further, it is desirable that said second electrodes are formed by a photolithography process or a laser process, and said first electrodes are formed by a laser process after the second electrodes are formed by the photolithography process or the laser process.
Further, it is desirable that said first electrodes are made of the transparent material, such as ITO or SnO2, and said second electrodes are made of a material, such as Ag or Cr/Cu/Cr layers, the resistance value of such material being lower than that of the transparent material.
When the first electrodes are to be formed to have a rectangular form, this can be accomplished by scanning the beam or the stage of the laser equipment in a constant direction, such as the X direction. Therefore, the overall manufacturing throughput according to this invention is improved as compared to conventional manufacture of a display device which has obliquely directed wiring. Also, when the first electrode is film-formed material on a limited area of the substrate, rather than on the whole area of the substrate, it is possible to reduce the material cost in addition to improving the throughput. This is because it is possible to form the first electrodes into a rectangle of an optimum size by scanning the beam or the stage of the laser equipment in a constant direction, such as the X direction.
In this case, to obtain a certain discharging phenomenon, it is desirable for the first electrode material layer to be film-formed to cover the gas discharging area. Also, when the second electrode material is film-formed after processing the first electrode, the particles which adhere to the first electrode at the time of laser manufacture influence the formation of the second electrode. Therefore, it is desirable that the first electrode material and the second electrode material are film-formed, respectively, the second electrode being formed by a photolithography process or a laser process, and the first electrode being formed by a laser process after forming the second electrode. As a result, breakage of the second electrode can be suppressed.